<!--
 * @Author: sunshineGO 2943102883@qq.com
 * @Date: 2022-11-14 21:10:41
 * @LastEditors: 李季 2943102883@qq.com
 * @LastEditTime: 2022-11-14 22:25:59
 * @FilePath: /miniapp-parent/Users/macbook/Desktop/myProject/love.html
 * @Description: 
 * 
 * Copyright (c) 2022 by sunshineGO 2943102883@qq.com, All Rights Reserved. 
-->
<!DOCTYPE html>
<html lang="en">
  <head>
    <title>New Document</title>
    <meta name="Generator" content="EditPlus" />
    <meta name="Author" content="" />
    <meta name="Keywords" content="" />
    <meta name="Description" content="" />
  </head>
  <style>
    html,
    body {
      height: 100%;
      padding: 0;
      margin: 0;
      background: #000;
    }
    canvas {
      position: absolute;
      width: 100%;
      height: 100%;
    }
  </style>
  <body>
    <canvas id="pinkboard"></canvas>
    <script>
      /*
       * 配置项
       */
      const settings = {
        particles: {
          length: 500, // 长度
          duration: 2, // 持续时间
          velocity: 100, // 速度
          effect: -0.75, // 偏移
          size: 30, // 例子大小
          loveColor: '#ea80b0' // 爱心颜色
        }
      }

      /*
       * 使用requestAnimationFrame 代替setTimeout，优化性能
       */
      ;(function () {
        let b = 0
        let c = ['ms', 'moz', 'webkit', 'o']
        for (let a = 0; a < c.length && !window.requestAnimationFrame; ++a) {
          window.requestAnimationFrame = window[c[a] + 'RequestAnimationFrame']
          window.cancelAnimationFrame =
            window[c[a] + 'CancelAnimationFrame'] || window[c[a] + 'CancelRequestAnimationFrame']
        }
        if (!window.requestAnimationFrame) {
          window.requestAnimationFrame = function (h, e) {
            let d = new Date().getTime()
            let f = Math.max(0, 16 - (d - b))
            let g = window.setTimeout(function () {
              h(d + f)
            }, f)
            b = d + f
            return g
          }
        }
        if (!window.cancelAnimationFrame) {
          window.cancelAnimationFrame = function (d) {
            clearTimeout(d)
          }
        }
      })()

      /*
       * Point类
       */
      class Point {
        constructor(x, y) {
          this.x = typeof x !== 'undefined' ? x : 0
          this.y = typeof y !== 'undefined' ? y : 0
        }
        clone() {
          return new Point(this.x, this.y)
        }
        length(length) {
          if (typeof length == 'undefined') return Math.sqrt(this.x * this.x + this.y * this.y)
          this.normalize()
          this.x *= length
          this.y *= length
          return this
        }
        normalize() {
          let length = this.length()
          this.x /= length
          this.y /= length
          return this
        }
      }

      /*
       * 粒子类
       */
      class Particle {
        constructor() {
          this.position = new Point()
          this.velocity = new Point()
          this.acceleration = new Point()
          this.age = 0
        }
        initialize(x, y, dx, dy) {
          // 初始化
          this.position.x = x
          this.position.y = y
          this.velocity.x = dx
          this.velocity.y = dy
          this.acceleration.x = dx * settings.particles.effect
          this.acceleration.y = dy * settings.particles.effect
          this.age = 0
        }
        update(deltaTime) {
          // 更新
          this.position.x += this.velocity.x * deltaTime
          this.position.y += this.velocity.y * deltaTime
          this.velocity.x += this.acceleration.x * deltaTime
          this.velocity.y += this.acceleration.y * deltaTime
          this.age += deltaTime
        }
        draw(context, image) {
          // 绘制
          function ease(t) {
            return --t * t * t + 1
          }
          let size = image.width * ease(this.age / settings.particles.duration)
          context.globalAlpha = 1 - this.age / settings.particles.duration
          context.drawImage(
            image,
            this.position.x - size / 2,
            this.position.y - size / 2,
            size,
            size
          )
        }
      }

      /*
       * 粒子池
       */
      class ParticlePool {
        constructor(length) {
          this.particles = []
          this.firstActive = 0
          this.firstFree = 0
          this.duration = settings.particles.duration
          // 创建并且填充粒子
          this.particles = new Array(length)
          for (let i = 0; i < this.particles.length; i++) this.particles[i] = new Particle()
        }
        add(x, y, dx, dy) {
          this.particles[this.firstFree].initialize(x, y, dx, dy)
          // 处理队列
          this.firstFree++
          if (this.firstFree == this.particles.length) this.firstFree = 0
          if (this.firstActive == this.firstFree) this.firstActive++
          if (this.firstActive == this.particles.length) this.firstActive = 0
        }
        update(deltaTime) {
          let i
          // 更新爱心粒子
          if (this.firstActive < this.firstFree) {
            for (let i = this.firstActive; i < this.firstFree; i++)
              this.particles[i].update(deltaTime)
          }
          if (this.firstFree < this.firstActive) {
            for (let i = this.firstActive; i < this.particles.length; i++)
              this.particles[i].update(deltaTime)
            for (let i = 0; i < this.firstFree; i++) this.particles[i].update(deltaTime)
          }
          // 删除边缘粒子
          while (
            this.particles[this.firstActive].age >= this.duration &&
            this.firstActive != this.firstFree
          ) {
            this.firstActive++
            if (this.firstActive == this.particles.length) this.firstActive = 0
          }
        }
        draw(context, image) {
          // 绘制粒子
          if (this.firstActive < this.firstFree) {
            for (let i = this.firstActive; i < this.firstFree; i++)
              this.particles[i].draw(context, image)
          }
          if (this.firstFree < this.firstActive) {
            for (let i = this.firstActive; i < this.particles.length; i++)
              this.particles[i].draw(context, image)
            for (let i = 0; i < this.firstFree; i++) this.particles[i].draw(context, image)
          }
        }
      }

      /*
       * main
       */
      ;(function (canvas) {
        let context = canvas.getContext('2d')
        let particles = new ParticlePool(settings.particles.length)
        let particleRate = settings.particles.length / settings.particles.duration // particles/sec
        let time
        // 初始化
        function pointOnHeart(t) {
          return new Point(
            160 * Math.pow(Math.sin(t), 3),
            130 * Math.cos(t) -
              50 * Math.cos(2 * t) -
              20 * Math.cos(3 * t) -
              10 * Math.cos(4 * t) +
              25
          )
        }
        // 用一个虚拟的canvas创建粒子图片
        let image = (function () {
          let canvas = document.createElement('canvas')
          let context = canvas.getContext('2d')
          canvas.width = settings.particles.size
          canvas.height = settings.particles.size
          function to(t) {
            let point = pointOnHeart(t)
            point.x = settings.particles.size / 2 + (point.x * settings.particles.size) / 350
            point.y = settings.particles.size / 2 - (point.y * settings.particles.size) / 350
            return point
          }
          // 创建路径
          context.beginPath()
          let t = -Math.PI
          let point = to(t)
          context.moveTo(point.x, point.y)
          while (t < Math.PI) {
            t += 0.01 // 精度为0.01
            point = to(t)
            context.lineTo(point.x, point.y)
          }
          context.closePath()
          // 绘制路径
          context.fillStyle = settings.particles.loveColor
          context.fill()
          // 返回图片
          let image = new Image()
          image.src = canvas.toDataURL()
          return image
        })()
        // 渲染
        function render() {
          // 清除画布
          requestAnimationFrame(render)
          // 更新
          let newTime = new Date().getTime() / 1000,
            deltaTime = newTime - (time || newTime)
          time = newTime
          // clear
          context.clearRect(0, 0, canvas.width, canvas.height)
          // 创建新的粒子
          let amount = particleRate * deltaTime
          for (let i = 0; i < amount; i++) {
            let pos = pointOnHeart(Math.PI - 2 * Math.PI * Math.random())
            let dir = pos.clone().length(settings.particles.velocity)
            particles.add(canvas.width / 2 + pos.x, canvas.height / 2 - pos.y, dir.x, -dir.y)
          }
          // 更新和绘制粒子
          particles.update(deltaTime)
          particles.draw(context, image)
        }
        // 处理画布
        function onResize() {
          canvas.width = canvas.clientWidth
          canvas.height = canvas.clientHeight
        }
        window.onresize = onResize
        // 延迟渲染
        setTimeout(function () {
          onResize()
          render()
        }, 10)
      })(document.getElementById('pinkboard'))
    </script>
  </body>
</html>
